/*
 * Copyright (c) 1996, 2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */

package java.io;

import java.util.Objects;
import java.util.Formatter;
import java.util.Locale;
import java.nio.charset.Charset;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.UnsupportedCharsetException;

/**
 * Prints formatted representations of objects to a text-output stream.  This
 * class implements all of the <tt>print</tt> methods found in {@link
 * PrintStream}.  It does not contain methods for writing raw bytes, for which
 * a program should use unencoded byte streams.
 *
 * <p> Unlike the {@link PrintStream} class, if automatic flushing is enabled
 * it will be done only when one of the <tt>println</tt>, <tt>printf</tt>, or
 * <tt>format</tt> methods is invoked, rather than whenever a newline character
 * happens to be output.  These methods use the platform's own notion of line
 * separator rather than the newline character.
 *
 * <p> Methods in this class never throw I/O exceptions, although some of its
 * constructors may.  The client may inquire as to whether any errors have
 * occurred by invoking {@link #checkError checkError()}.
 *
 * @author Frank Yellin
 * @author Mark Reinhold
 * @since JDK1.1
 */

public class PrintWriter extends Writer {

  /**
   * The underlying character-output stream of this
   * <code>PrintWriter</code>.
   *
   * @since 1.2
   */
  protected Writer out;

  private final boolean autoFlush;
  private boolean trouble = false;
  private Formatter formatter;
  private PrintStream psOut = null;

  /**
   * Line separator string.  This is the value of the line.separator
   * property at the moment that the stream was created.
   */
  private final String lineSeparator;

  /**
   * Returns a charset object for the given charset name.
   *
   * @throws NullPointerException is csn is null
   * @throws UnsupportedEncodingException if the charset is not supported
   */
  private static Charset toCharset(String csn)
      throws UnsupportedEncodingException {
    Objects.requireNonNull(csn, "charsetName");
    try {
      return Charset.forName(csn);
    } catch (IllegalCharsetNameException | UnsupportedCharsetException unused) {
      // UnsupportedEncodingException should be thrown
      throw new UnsupportedEncodingException(csn);
    }
  }

  /**
   * Creates a new PrintWriter, without automatic line flushing.
   *
   * @param out A character-output stream
   */
  public PrintWriter(Writer out) {
    this(out, false);
  }

  /**
   * Creates a new PrintWriter.
   *
   * @param out A character-output stream
   * @param autoFlush A boolean; if true, the <tt>println</tt>, <tt>printf</tt>, or <tt>format</tt>
   * methods will flush the output buffer
   */
  public PrintWriter(Writer out,
      boolean autoFlush) {
    super(out);
    this.out = out;
    this.autoFlush = autoFlush;
    lineSeparator = java.security.AccessController.doPrivileged(
        new sun.security.action.GetPropertyAction("line.separator"));
  }

  /**
   * Creates a new PrintWriter, without automatic line flushing, from an
   * existing OutputStream.  This convenience constructor creates the
   * necessary intermediate OutputStreamWriter, which will convert characters
   * into bytes using the default character encoding.
   *
   * @param out An output stream
   * @see java.io.OutputStreamWriter#OutputStreamWriter(java.io.OutputStream)
   */
  public PrintWriter(OutputStream out) {
    this(out, false);
  }

  /**
   * Creates a new PrintWriter from an existing OutputStream.  This
   * convenience constructor creates the necessary intermediate
   * OutputStreamWriter, which will convert characters into bytes using the
   * default character encoding.
   *
   * @param out An output stream
   * @param autoFlush A boolean; if true, the <tt>println</tt>, <tt>printf</tt>, or <tt>format</tt>
   * methods will flush the output buffer
   * @see java.io.OutputStreamWriter#OutputStreamWriter(java.io.OutputStream)
   */
  public PrintWriter(OutputStream out, boolean autoFlush) {
    this(new BufferedWriter(new OutputStreamWriter(out)), autoFlush);

    // save print stream for error propagation
    if (out instanceof java.io.PrintStream) {
      psOut = (PrintStream) out;
    }
  }

  /**
   * Creates a new PrintWriter, without automatic line flushing, with the
   * specified file name.  This convenience constructor creates the necessary
   * intermediate {@link java.io.OutputStreamWriter OutputStreamWriter},
   * which will encode characters using the {@linkplain
   * java.nio.charset.Charset#defaultCharset() default charset} for this
   * instance of the Java virtual machine.
   *
   * @param fileName The name of the file to use as the destination of this writer. If the file
   * exists then it will be truncated to zero size; otherwise, a new file will be created.  The
   * output will be written to the file and is buffered.
   * @throws FileNotFoundException If the given string does not denote an existing, writable regular
   * file and a new regular file of that name cannot be created, or if some other error occurs while
   * opening or creating the file
   * @throws SecurityException If a security manager is present and {@link
   * SecurityManager#checkWrite checkWrite(fileName)} denies write access to the file
   * @since 1.5
   */
  public PrintWriter(String fileName) throws FileNotFoundException {
    this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(fileName))),
        false);
  }

  /* Private constructor */
  private PrintWriter(Charset charset, File file)
      throws FileNotFoundException {
    this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file), charset)),
        false);
  }

  /**
   * Creates a new PrintWriter, without automatic line flushing, with the
   * specified file name and charset.  This convenience constructor creates
   * the necessary intermediate {@link java.io.OutputStreamWriter
   * OutputStreamWriter}, which will encode characters using the provided
   * charset.
   *
   * @param fileName The name of the file to use as the destination of this writer. If the file
   * exists then it will be truncated to zero size; otherwise, a new file will be created.  The
   * output will be written to the file and is buffered.
   * @param csn The name of a supported {@linkplain java.nio.charset.Charset charset}
   * @throws FileNotFoundException If the given string does not denote an existing, writable regular
   * file and a new regular file of that name cannot be created, or if some other error occurs while
   * opening or creating the file
   * @throws SecurityException If a security manager is present and {@link
   * SecurityManager#checkWrite checkWrite(fileName)} denies write access to the file
   * @throws UnsupportedEncodingException If the named charset is not supported
   * @since 1.5
   */
  public PrintWriter(String fileName, String csn)
      throws FileNotFoundException, UnsupportedEncodingException {
    this(toCharset(csn), new File(fileName));
  }

  /**
   * Creates a new PrintWriter, without automatic line flushing, with the
   * specified file.  This convenience constructor creates the necessary
   * intermediate {@link java.io.OutputStreamWriter OutputStreamWriter},
   * which will encode characters using the {@linkplain
   * java.nio.charset.Charset#defaultCharset() default charset} for this
   * instance of the Java virtual machine.
   *
   * @param file The file to use as the destination of this writer.  If the file exists then it will
   * be truncated to zero size; otherwise, a new file will be created.  The output will be written
   * to the file and is buffered.
   * @throws FileNotFoundException If the given file object does not denote an existing, writable
   * regular file and a new regular file of that name cannot be created, or if some other error
   * occurs while opening or creating the file
   * @throws SecurityException If a security manager is present and {@link
   * SecurityManager#checkWrite checkWrite(file.getPath())} denies write access to the file
   * @since 1.5
   */
  public PrintWriter(File file) throws FileNotFoundException {
    this(new BufferedWriter(new OutputStreamWriter(new FileOutputStream(file))),
        false);
  }

  /**
   * Creates a new PrintWriter, without automatic line flushing, with the
   * specified file and charset.  This convenience constructor creates the
   * necessary intermediate {@link java.io.OutputStreamWriter
   * OutputStreamWriter}, which will encode characters using the provided
   * charset.
   *
   * @param file The file to use as the destination of this writer.  If the file exists then it will
   * be truncated to zero size; otherwise, a new file will be created.  The output will be written
   * to the file and is buffered.
   * @param csn The name of a supported {@linkplain java.nio.charset.Charset charset}
   * @throws FileNotFoundException If the given file object does not denote an existing, writable
   * regular file and a new regular file of that name cannot be created, or if some other error
   * occurs while opening or creating the file
   * @throws SecurityException If a security manager is present and {@link
   * SecurityManager#checkWrite checkWrite(file.getPath())} denies write access to the file
   * @throws UnsupportedEncodingException If the named charset is not supported
   * @since 1.5
   */
  public PrintWriter(File file, String csn)
      throws FileNotFoundException, UnsupportedEncodingException {
    this(toCharset(csn), file);
  }

  /**
   * Checks to make sure that the stream has not been closed
   */
  private void ensureOpen() throws IOException {
    if (out == null) {
      throw new IOException("Stream closed");
    }
  }

  /**
   * Flushes the stream.
   *
   * @see #checkError()
   */
  public void flush() {
    try {
      synchronized (lock) {
        ensureOpen();
        out.flush();
      }
    } catch (IOException x) {
      trouble = true;
    }
  }

  /**
   * Closes the stream and releases any system resources associated
   * with it. Closing a previously closed stream has no effect.
   *
   * @see #checkError()
   */
  public void close() {
    try {
      synchronized (lock) {
        if (out == null) {
          return;
        }
        out.close();
        out = null;
      }
    } catch (IOException x) {
      trouble = true;
    }
  }

  /**
   * Flushes the stream if it's not closed and checks its error state.
   *
   * @return <code>true</code> if the print stream has encountered an error, either on the
   * underlying output stream or during a format conversion.
   */
  public boolean checkError() {
    if (out != null) {
      flush();
    }
    if (out instanceof java.io.PrintWriter) {
      PrintWriter pw = (PrintWriter) out;
      return pw.checkError();
    } else if (psOut != null) {
      return psOut.checkError();
    }
    return trouble;
  }

  /**
   * Indicates that an error has occurred.
   *
   * <p> This method will cause subsequent invocations of {@link
   * #checkError()} to return <tt>true</tt> until {@link
   * #clearError()} is invoked.
   */
  protected void setError() {
    trouble = true;
  }

  /**
   * Clears the error state of this stream.
   *
   * <p> This method will cause subsequent invocations of {@link
   * #checkError()} to return <tt>false</tt> until another write
   * operation fails and invokes {@link #setError()}.
   *
   * @since 1.6
   */
  protected void clearError() {
    trouble = false;
  }

    /*
     * Exception-catching, synchronized output operations,
     * which also implement the write() methods of Writer
     */

  /**
   * Writes a single character.
   *
   * @param c int specifying a character to be written.
   */
  public void write(int c) {
    try {
      synchronized (lock) {
        ensureOpen();
        out.write(c);
      }
    } catch (InterruptedIOException x) {
      Thread.currentThread().interrupt();
    } catch (IOException x) {
      trouble = true;
    }
  }

  /**
   * Writes A Portion of an array of characters.
   *
   * @param buf Array of characters
   * @param off Offset from which to start writing characters
   * @param len Number of characters to write
   */
  public void write(char buf[], int off, int len) {
    try {
      synchronized (lock) {
        ensureOpen();
        out.write(buf, off, len);
      }
    } catch (InterruptedIOException x) {
      Thread.currentThread().interrupt();
    } catch (IOException x) {
      trouble = true;
    }
  }

  /**
   * Writes an array of characters.  This method cannot be inherited from the
   * Writer class because it must suppress I/O exceptions.
   *
   * @param buf Array of characters to be written
   */
  public void write(char buf[]) {
    write(buf, 0, buf.length);
  }

  /**
   * Writes a portion of a string.
   *
   * @param s A String
   * @param off Offset from which to start writing characters
   * @param len Number of characters to write
   */
  public void write(String s, int off, int len) {
    try {
      synchronized (lock) {
        ensureOpen();
        out.write(s, off, len);
      }
    } catch (InterruptedIOException x) {
      Thread.currentThread().interrupt();
    } catch (IOException x) {
      trouble = true;
    }
  }

  /**
   * Writes a string.  This method cannot be inherited from the Writer class
   * because it must suppress I/O exceptions.
   *
   * @param s String to be written
   */
  public void write(String s) {
    write(s, 0, s.length());
  }

  private void newLine() {
    try {
      synchronized (lock) {
        ensureOpen();
        out.write(lineSeparator);
        if (autoFlush) {
          out.flush();
        }
      }
    } catch (InterruptedIOException x) {
      Thread.currentThread().interrupt();
    } catch (IOException x) {
      trouble = true;
    }
  }

    /* Methods that do not terminate lines */

  /**
   * Prints a boolean value.  The string produced by <code>{@link
   * java.lang.String#valueOf(boolean)}</code> is translated into bytes
   * according to the platform's default character encoding, and these bytes
   * are written in exactly the manner of the <code>{@link
   * #write(int)}</code> method.
   *
   * @param b The <code>boolean</code> to be printed
   */
  public void print(boolean b) {
    write(b ? "true" : "false");
  }

  /**
   * Prints a character.  The character is translated into one or more bytes
   * according to the platform's default character encoding, and these bytes
   * are written in exactly the manner of the <code>{@link
   * #write(int)}</code> method.
   *
   * @param c The <code>char</code> to be printed
   */
  public void print(char c) {
    write(c);
  }

  /**
   * Prints an integer.  The string produced by <code>{@link
   * java.lang.String#valueOf(int)}</code> is translated into bytes according
   * to the platform's default character encoding, and these bytes are
   * written in exactly the manner of the <code>{@link #write(int)}</code>
   * method.
   *
   * @param i The <code>int</code> to be printed
   * @see java.lang.Integer#toString(int)
   */
  public void print(int i) {
    write(String.valueOf(i));
  }

  /**
   * Prints a long integer.  The string produced by <code>{@link
   * java.lang.String#valueOf(long)}</code> is translated into bytes
   * according to the platform's default character encoding, and these bytes
   * are written in exactly the manner of the <code>{@link #write(int)}</code>
   * method.
   *
   * @param l The <code>long</code> to be printed
   * @see java.lang.Long#toString(long)
   */
  public void print(long l) {
    write(String.valueOf(l));
  }

  /**
   * Prints a floating-point number.  The string produced by <code>{@link
   * java.lang.String#valueOf(float)}</code> is translated into bytes
   * according to the platform's default character encoding, and these bytes
   * are written in exactly the manner of the <code>{@link #write(int)}</code>
   * method.
   *
   * @param f The <code>float</code> to be printed
   * @see java.lang.Float#toString(float)
   */
  public void print(float f) {
    write(String.valueOf(f));
  }

  /**
   * Prints a double-precision floating-point number.  The string produced by
   * <code>{@link java.lang.String#valueOf(double)}</code> is translated into
   * bytes according to the platform's default character encoding, and these
   * bytes are written in exactly the manner of the <code>{@link
   * #write(int)}</code> method.
   *
   * @param d The <code>double</code> to be printed
   * @see java.lang.Double#toString(double)
   */
  public void print(double d) {
    write(String.valueOf(d));
  }

  /**
   * Prints an array of characters.  The characters are converted into bytes
   * according to the platform's default character encoding, and these bytes
   * are written in exactly the manner of the <code>{@link #write(int)}</code>
   * method.
   *
   * @param s The array of chars to be printed
   * @throws NullPointerException If <code>s</code> is <code>null</code>
   */
  public void print(char s[]) {
    write(s);
  }

  /**
   * Prints a string.  If the argument is <code>null</code> then the string
   * <code>"null"</code> is printed.  Otherwise, the string's characters are
   * converted into bytes according to the platform's default character
   * encoding, and these bytes are written in exactly the manner of the
   * <code>{@link #write(int)}</code> method.
   *
   * @param s The <code>String</code> to be printed
   */
  public void print(String s) {
    if (s == null) {
      s = "null";
    }
    write(s);
  }

  /**
   * Prints an object.  The string produced by the <code>{@link
   * java.lang.String#valueOf(Object)}</code> method is translated into bytes
   * according to the platform's default character encoding, and these bytes
   * are written in exactly the manner of the <code>{@link #write(int)}</code>
   * method.
   *
   * @param obj The <code>Object</code> to be printed
   * @see java.lang.Object#toString()
   */
  public void print(Object obj) {
    write(String.valueOf(obj));
  }

    /* Methods that do terminate lines */

  /**
   * Terminates the current line by writing the line separator string.  The
   * line separator string is defined by the system property
   * <code>line.separator</code>, and is not necessarily a single newline
   * character (<code>'\n'</code>).
   */
  public void println() {
    newLine();
  }

  /**
   * Prints a boolean value and then terminates the line.  This method behaves
   * as though it invokes <code>{@link #print(boolean)}</code> and then
   * <code>{@link #println()}</code>.
   *
   * @param x the <code>boolean</code> value to be printed
   */
  public void println(boolean x) {
    synchronized (lock) {
      print(x);
      println();
    }
  }

  /**
   * Prints a character and then terminates the line.  This method behaves as
   * though it invokes <code>{@link #print(char)}</code> and then <code>{@link
   * #println()}</code>.
   *
   * @param x the <code>char</code> value to be printed
   */
  public void println(char x) {
    synchronized (lock) {
      print(x);
      println();
    }
  }

  /**
   * Prints an integer and then terminates the line.  This method behaves as
   * though it invokes <code>{@link #print(int)}</code> and then <code>{@link
   * #println()}</code>.
   *
   * @param x the <code>int</code> value to be printed
   */
  public void println(int x) {
    synchronized (lock) {
      print(x);
      println();
    }
  }

  /**
   * Prints a long integer and then terminates the line.  This method behaves
   * as though it invokes <code>{@link #print(long)}</code> and then
   * <code>{@link #println()}</code>.
   *
   * @param x the <code>long</code> value to be printed
   */
  public void println(long x) {
    synchronized (lock) {
      print(x);
      println();
    }
  }

  /**
   * Prints a floating-point number and then terminates the line.  This method
   * behaves as though it invokes <code>{@link #print(float)}</code> and then
   * <code>{@link #println()}</code>.
   *
   * @param x the <code>float</code> value to be printed
   */
  public void println(float x) {
    synchronized (lock) {
      print(x);
      println();
    }
  }

  /**
   * Prints a double-precision floating-point number and then terminates the
   * line.  This method behaves as though it invokes <code>{@link
   * #print(double)}</code> and then <code>{@link #println()}</code>.
   *
   * @param x the <code>double</code> value to be printed
   */
  public void println(double x) {
    synchronized (lock) {
      print(x);
      println();
    }
  }

  /**
   * Prints an array of characters and then terminates the line.  This method
   * behaves as though it invokes <code>{@link #print(char[])}</code> and then
   * <code>{@link #println()}</code>.
   *
   * @param x the array of <code>char</code> values to be printed
   */
  public void println(char x[]) {
    synchronized (lock) {
      print(x);
      println();
    }
  }

  /**
   * Prints a String and then terminates the line.  This method behaves as
   * though it invokes <code>{@link #print(String)}</code> and then
   * <code>{@link #println()}</code>.
   *
   * @param x the <code>String</code> value to be printed
   */
  public void println(String x) {
    synchronized (lock) {
      print(x);
      println();
    }
  }

  /**
   * Prints an Object and then terminates the line.  This method calls
   * at first String.valueOf(x) to get the printed object's string value,
   * then behaves as
   * though it invokes <code>{@link #print(String)}</code> and then
   * <code>{@link #println()}</code>.
   *
   * @param x The <code>Object</code> to be printed.
   */
  public void println(Object x) {
    String s = String.valueOf(x);
    synchronized (lock) {
      print(s);
      println();
    }
  }

  /**
   * A convenience method to write a formatted string to this writer using
   * the specified format string and arguments.  If automatic flushing is
   * enabled, calls to this method will flush the output buffer.
   *
   * <p> An invocation of this method of the form <tt>out.printf(format,
   * args)</tt> behaves in exactly the same way as the invocation
   *
   * <pre>
   *     out.format(format, args) </pre>
   *
   * @param format A format string as described in <a href="../util/Formatter.html#syntax">Format
   * string syntax</a>.
   * @param args Arguments referenced by the format specifiers in the format string.  If there are
   * more arguments than format specifiers, the extra arguments are ignored.  The number of
   * arguments is variable and may be zero.  The maximum number of arguments is limited by the
   * maximum dimension of a Java array as defined by <cite>The Java&trade; Virtual Machine
   * Specification</cite>. The behaviour on a <tt>null</tt> argument depends on the <a
   * href="../util/Formatter.html#syntax">conversion</a>.
   * @return This writer
   * @throws java.util.IllegalFormatException If a format string contains an illegal syntax, a
   * format specifier that is incompatible with the given arguments, insufficient arguments given
   * the format string, or other illegal conditions.  For specification of all possible formatting
   * errors, see the <a href="../util/Formatter.html#detail">Details</a> section of the formatter
   * class specification.
   * @throws NullPointerException If the <tt>format</tt> is <tt>null</tt>
   * @since 1.5
   */
  public PrintWriter printf(String format, Object... args) {
    return format(format, args);
  }

  /**
   * A convenience method to write a formatted string to this writer using
   * the specified format string and arguments.  If automatic flushing is
   * enabled, calls to this method will flush the output buffer.
   *
   * <p> An invocation of this method of the form <tt>out.printf(l, format,
   * args)</tt> behaves in exactly the same way as the invocation
   *
   * <pre>
   *     out.format(l, format, args) </pre>
   *
   * @param l The {@linkplain java.util.Locale locale} to apply during formatting.  If <tt>l</tt> is
   * <tt>null</tt> then no localization is applied.
   * @param format A format string as described in <a href="../util/Formatter.html#syntax">Format
   * string syntax</a>.
   * @param args Arguments referenced by the format specifiers in the format string.  If there are
   * more arguments than format specifiers, the extra arguments are ignored.  The number of
   * arguments is variable and may be zero.  The maximum number of arguments is limited by the
   * maximum dimension of a Java array as defined by <cite>The Java&trade; Virtual Machine
   * Specification</cite>. The behaviour on a <tt>null</tt> argument depends on the <a
   * href="../util/Formatter.html#syntax">conversion</a>.
   * @return This writer
   * @throws java.util.IllegalFormatException If a format string contains an illegal syntax, a
   * format specifier that is incompatible with the given arguments, insufficient arguments given
   * the format string, or other illegal conditions.  For specification of all possible formatting
   * errors, see the <a href="../util/Formatter.html#detail">Details</a> section of the formatter
   * class specification.
   * @throws NullPointerException If the <tt>format</tt> is <tt>null</tt>
   * @since 1.5
   */
  public PrintWriter printf(Locale l, String format, Object... args) {
    return format(l, format, args);
  }

  /**
   * Writes a formatted string to this writer using the specified format
   * string and arguments.  If automatic flushing is enabled, calls to this
   * method will flush the output buffer.
   *
   * <p> The locale always used is the one returned by {@link
   * java.util.Locale#getDefault() Locale.getDefault()}, regardless of any
   * previous invocations of other formatting methods on this object.
   *
   * @param format A format string as described in <a href="../util/Formatter.html#syntax">Format
   * string syntax</a>.
   * @param args Arguments referenced by the format specifiers in the format string.  If there are
   * more arguments than format specifiers, the extra arguments are ignored.  The number of
   * arguments is variable and may be zero.  The maximum number of arguments is limited by the
   * maximum dimension of a Java array as defined by <cite>The Java&trade; Virtual Machine
   * Specification</cite>. The behaviour on a <tt>null</tt> argument depends on the <a
   * href="../util/Formatter.html#syntax">conversion</a>.
   * @return This writer
   * @throws java.util.IllegalFormatException If a format string contains an illegal syntax, a
   * format specifier that is incompatible with the given arguments, insufficient arguments given
   * the format string, or other illegal conditions.  For specification of all possible formatting
   * errors, see the <a href="../util/Formatter.html#detail">Details</a> section of the Formatter
   * class specification.
   * @throws NullPointerException If the <tt>format</tt> is <tt>null</tt>
   * @since 1.5
   */
  public PrintWriter format(String format, Object... args) {
    try {
      synchronized (lock) {
        ensureOpen();
        if ((formatter == null)
            || (formatter.locale() != Locale.getDefault())) {
          formatter = new Formatter(this);
        }
        formatter.format(Locale.getDefault(), format, args);
        if (autoFlush) {
          out.flush();
        }
      }
    } catch (InterruptedIOException x) {
      Thread.currentThread().interrupt();
    } catch (IOException x) {
      trouble = true;
    }
    return this;
  }

  /**
   * Writes a formatted string to this writer using the specified format
   * string and arguments.  If automatic flushing is enabled, calls to this
   * method will flush the output buffer.
   *
   * @param l The {@linkplain java.util.Locale locale} to apply during formatting.  If <tt>l</tt> is
   * <tt>null</tt> then no localization is applied.
   * @param format A format string as described in <a href="../util/Formatter.html#syntax">Format
   * string syntax</a>.
   * @param args Arguments referenced by the format specifiers in the format string.  If there are
   * more arguments than format specifiers, the extra arguments are ignored.  The number of
   * arguments is variable and may be zero.  The maximum number of arguments is limited by the
   * maximum dimension of a Java array as defined by <cite>The Java&trade; Virtual Machine
   * Specification</cite>. The behaviour on a <tt>null</tt> argument depends on the <a
   * href="../util/Formatter.html#syntax">conversion</a>.
   * @return This writer
   * @throws java.util.IllegalFormatException If a format string contains an illegal syntax, a
   * format specifier that is incompatible with the given arguments, insufficient arguments given
   * the format string, or other illegal conditions.  For specification of all possible formatting
   * errors, see the <a href="../util/Formatter.html#detail">Details</a> section of the formatter
   * class specification.
   * @throws NullPointerException If the <tt>format</tt> is <tt>null</tt>
   * @since 1.5
   */
  public PrintWriter format(Locale l, String format, Object... args) {
    try {
      synchronized (lock) {
        ensureOpen();
        if ((formatter == null) || (formatter.locale() != l)) {
          formatter = new Formatter(this, l);
        }
        formatter.format(l, format, args);
        if (autoFlush) {
          out.flush();
        }
      }
    } catch (InterruptedIOException x) {
      Thread.currentThread().interrupt();
    } catch (IOException x) {
      trouble = true;
    }
    return this;
  }

  /**
   * Appends the specified character sequence to this writer.
   *
   * <p> An invocation of this method of the form <tt>out.append(csq)</tt>
   * behaves in exactly the same way as the invocation
   *
   * <pre>
   *     out.write(csq.toString()) </pre>
   *
   * <p> Depending on the specification of <tt>toString</tt> for the
   * character sequence <tt>csq</tt>, the entire sequence may not be
   * appended. For instance, invoking the <tt>toString</tt> method of a
   * character buffer will return a subsequence whose content depends upon
   * the buffer's position and limit.
   *
   * @param csq The character sequence to append.  If <tt>csq</tt> is <tt>null</tt>, then the four
   * characters <tt>"null"</tt> are appended to this writer.
   * @return This writer
   * @since 1.5
   */
  public PrintWriter append(CharSequence csq) {
    if (csq == null) {
      write("null");
    } else {
      write(csq.toString());
    }
    return this;
  }

  /**
   * Appends a subsequence of the specified character sequence to this writer.
   *
   * <p> An invocation of this method of the form <tt>out.append(csq, start,
   * end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in
   * exactly the same way as the invocation
   *
   * <pre>
   *     out.write(csq.subSequence(start, end).toString()) </pre>
   *
   * @param csq The character sequence from which a subsequence will be appended.  If <tt>csq</tt>
   * is <tt>null</tt>, then characters will be appended as if <tt>csq</tt> contained the four
   * characters <tt>"null"</tt>.
   * @param start The index of the first character in the subsequence
   * @param end The index of the character following the last character in the subsequence
   * @return This writer
   * @throws IndexOutOfBoundsException If <tt>start</tt> or <tt>end</tt> are negative,
   * <tt>start</tt> is greater than <tt>end</tt>, or <tt>end</tt> is greater than
   * <tt>csq.length()</tt>
   * @since 1.5
   */
  public PrintWriter append(CharSequence csq, int start, int end) {
    CharSequence cs = (csq == null ? "null" : csq);
    write(cs.subSequence(start, end).toString());
    return this;
  }

  /**
   * Appends the specified character to this writer.
   *
   * <p> An invocation of this method of the form <tt>out.append(c)</tt>
   * behaves in exactly the same way as the invocation
   *
   * <pre>
   *     out.write(c) </pre>
   *
   * @param c The 16-bit character to append
   * @return This writer
   * @since 1.5
   */
  public PrintWriter append(char c) {
    write(c);
    return this;
  }
}
